Formlabs Announces Elastic Resin


I can’t remember the last time I saw a bubble in a poured silicone mold… but then, I am a moldmaker and I have a vacuum pump.

You CAN use this to produce printed molds- but the resin costs 8 times as much as tin cured silicones.
The the cost of one liter- I can buy 2 gallons of silicone.

I advise using the form 2 to print a CASING that accurately maintains a 3/16" gap between your master and the inner wall of the casing… ( no counting undercut areas where the rubber will be thicker for draft ) and then Pouring silicone into the gap.


You may be able to use a syringe or other pumping method to flush your small tubes before postcuring; I’ve done some experiments with long tubes and I find it works best for me to do this washing before I do general washing. Because the uncured elastic resin is so thick and viscous, the longer a tube gets the harder it is to purge out after printing. I wouldn’t rule it out, but it may not be an effect of laser light scattering into the part and curing the resin inside the tubes.

Depending on your exact dimensions, it may be tricky to avoid tearing the tube you’re trying to flush, and if you can align the length of the tubes with the peel/wipe direction, that may also help slightly.

Coloring the resin with a pigment or dye is possible, but not officially supported, and if you block too much of the light that’s curing the resin, then it just won’t print period. It’s possible that there’s a sweet spot that doesn’t inhibit layer-by-layer curing too much but does block light scattering into the already-cured part.


Though a little expensive, an ultrasonic knife such as this can work well for removing supports. It requires less force than even a sharp blade so the resulting surface finish is better.


Considering the comment regarding minimizing oxygen transport, does that imply not leaving a finished part on the build plate for a long period of time. This would make runs that do not finish during working hours difficult since they may be exposed to air for many hours (or days if over the weekend) before being able to cure.

So far have only made a couple of parts with the elastic material and they have been very tacky. I have not yet tried curing in a clear bag with water yet. I assume this will need a longer cure time since the water will need to come up to temperature. Any recommendations for that?


I’m pretty sure Ike’s comment on creating an oxygen barrier is only relevant to when you are actually post-curing the part, not before. Oxygen prevent proper reticulation of the resin by UV light.


@ralfieri JohnHue is correct - oxygen inhibiting the cure isn’t relevant to printed parts hanging out on the build platform for hours, or days after printing.

Anecdotally and unofficially, I’m not sure a heated post-cure is as important for Elastic resin as it is for other resins. That said, to get a heated, underwater cure with Elastic, I fill a plastic jar with hot tap water, and then run the cure with No Heat. I know that the water won’t cool off too much during the cure time. I find that about 10 minutes cure time is good at eliminating surface tack, and giving good enough tear strength. The officially-recommended 20 minutes should be good too, but beyond 20 minutes, you may see some yellowing.


I was so excited to get the sample of the elastic resin the other day (the arteries) because I was thinking it might be a lot of fun for jewelry applications. (Thinking back to the jewelry that kids wore in my childhood - ‘jelly’ bracelets and whatnot) But I was surprised that there seemed to be a lingering chemical scent on the cured sample piece Formlabs sent out, which makes me think a lot of people would find it unpleasant for jewelry.

Is this typical of this resin or does the scent eventually fade? Does the Flexible Resin have a scent post-cure? Inquiring minds would love to know!


The pinesol-esque scent is typical of Elastic, and while it might fade over time, it probably won’t go away entirely for the lifetime of the part. Also, generally, while most people have no problems handling parts printed on Form 2 and in some cases even wearing printed jewelry, most cured resins are not technically considered skin safe, especially in the long term. The only current exceptions are the biocompatible dental resins.

So, for jewelry applications for Elastic resins, one might want to look into dip coating them with a clear Silicone lacquer or something like that, which would make them safe for skin contact, and possibly contain the characteristic aroma of Elastic parts.


Ike, thanks for the info! Having never worked with elastic materials before, I’ll have to look into what options might exist for a home hobbyist to mold and cast something stretchy, instead of using the Formlabs elastic/flexible to print the wearables directly. People do tend to wear bracelets right on the skin, so I’d hate to cause an allergic reaction. Dental materials generally don’t have the kind of ‘flex’ that would have made the designs I had in mind entertaining, even though I do respect that they are the best synthetic option for anything worn long-term.

(Here’s to hoping reasonably flexible hypoallergenic materials exist and can be cast in non-industrial batch sizes in a small workshop. I’ve got some research to do!)


There are a lot of two-part mixture castable Silicone rubbers that are food and/or skin-safe. The biggest name is probably Smooth-On/Reynolds Advanced Materials, but there are plenty of others.

Formlabs has this webinar for some two-part silicone applications that might be relevant:

Unfortunately, I’m not familiar with the details off the top of my head for all the steps to do this yet, but I’ll probably wind up doing some kind of silicone rubber mold-making or part-casting someday.

We hope that for some cases like this, you and others will be able prototype your rubbery design by printing directly in Elastic, so that you can iterate through some improvements before making a mold to produce your final part.